[JS] Optimizing table sort and striping rows

[Anguz]

This script is from http://www.kryogenix.org/code/browser/sorttable/

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addEvent(window, "load", sortables_init);

var SORT_COLUMN_INDEX;

function sortables_init() {
    // Find all tables with class sortable and make them sortable
    if (!document.getElementsByTagName) return;
    tbls = document.getElementsByTagName("table");
    for (ti=0;ti<tbls.length;ti++) {
        thisTbl = tbls[ti];
        if (((' '+thisTbl.className+' ').indexOf("sortable") != -1) && (thisTbl.id)) {
            //initTable(thisTbl.id);
            ts_makeSortable(thisTbl);
        }
    }
}

function ts_makeSortable(table) {
    if (table.rows && table.rows.length > 0) {
        var firstRow = table.rows[0];
    }
    if (!firstRow) return;
   
    // We have a first row: assume it's the header, and make its contents clickable links
    for (var i=0;i<firstRow.cells.length;i++) {
        var cell = firstRow.cells[i];
        var txt = ts_getInnerText(cell);
        cell.innerHTML = '<a href="#" class="sortheader" onclick="ts_resortTable(this);return false;">'+txt+'<span class="sortarrow">&nbsp;&nbsp;</span></a>';
    }
}

function ts_getInnerText(el) {
if (typeof el == "string") return el;
if (typeof el == "undefined") { return el };
if (el.innerText) return el.innerText; //Not needed but it is faster
var str = "";

var cs = el.childNodes;
var l = cs.length;
for (var i = 0; i < l; i++) {
switch (cs[i].nodeType) {
case 1: //ELEMENT_NODE
str += ts_getInnerText(cs[i]);
break;
case 3: //TEXT_NODE
str += cs[i].nodeValue;
break;
}
}
return str;
}

function ts_resortTable(lnk) {
    // get the span
    var span;
    for (var ci=0;ci<lnk.childNodes.length;ci++) {
        if (lnk.childNodes[ci].tagName && lnk.childNodes[ci].tagName.toLowerCase() == 'span') span = lnk.childNodes[ci];
    }
    var spantext = ts_getInnerText(span);
    var td = lnk.parentNode;
    var column = td.cellIndex;
    var table = getParent(td,'TABLE');
   
    // Work out a type for the column
    if (table.rows.length <= 1) return;
    var itm = ts_getInnerText(table.rows[1].cells[column]);
    sortfn = ts_sort_caseinsensitive;
    if (itm.match(/^\d\d[\/-]\d\d[\/-]\d\d\d\d$/)) sortfn = ts_sort_date;
    if (itm.match(/^\d\d[\/-]\d\d[\/-]\d\d$/)) sortfn = ts_sort_date;
    if (itm.match(/^[£$]/)) sortfn = ts_sort_currency;
    if (itm.match(/^[\d\.]+$/)) sortfn = ts_sort_numeric;
    SORT_COLUMN_INDEX = column;
    var firstRow = new Array();
    var newRows = new Array();
    for (i=0;i<table.rows[0].length;i++) { firstRow[i] = table.rows[0][i]; }
    for (j=1;j<table.rows.length;j++) { newRows[j-1] = table.rows[j]; }

    newRows.sort(sortfn);

    if (span.getAttribute("sortdir") == 'down') {
        ARROW = '&nbsp;&darr;';
        newRows.reverse();
        span.setAttribute('sortdir','up');
    } else {
        ARROW = '&nbsp;&uarr;';
        span.setAttribute('sortdir','down');
    }
   
    // We appendChild rows that already exist to the tbody, so it moves them rather than creating new ones
    // don't do sortbottom rows
    for (i=0;i<newRows.length;i++) { if (!newRows[i].className || (newRows[i].className && (newRows[i].className.indexOf('sortbottom') == -1))) table.tBodies[0].appendChild(newRows[i]);}
    // do sortbottom rows only
    for (i=0;i<newRows.length;i++) { if (newRows[i].className && (newRows[i].className.indexOf('sortbottom') != -1)) table.tBodies[0].appendChild(newRows[i]);}
   
    // Delete any other arrows there may be showing
    var allspans = document.getElementsByTagName("span");
    for (var ci=0;ci<allspans.length;ci++) {
        if (allspans[ci].className == 'sortarrow') {
            if (getParent(allspans[ci],"table") == getParent(lnk,"table")) { // in the same table as us?
                allspans[ci].innerHTML = '&nbsp;&nbsp;';
            }
        }
    }
       
    span.innerHTML = ARROW;
}

function getParent(el, pTagName) {
if (el == null) return null;
else if (el.nodeType == 1 && el.tagName.toLowerCase() == pTagName.toLowerCase()) // Gecko bug, supposed to be uppercase
return el;
else
return getParent(el.parentNode, pTagName);
}
function ts_sort_date(a,b) {
    // y2k notes: two digit years less than 50 are treated as 20XX, greater than 50 are treated as 19XX
    aa = ts_getInnerText(a.cells[SORT_COLUMN_INDEX]);
    bb = ts_getInnerText(b.cells[SORT_COLUMN_INDEX]);
    if (aa.length == 10) {
        dt1 = aa.substr(6,4)+aa.substr(3,2)+aa.substr(0,2);
    } else {
        yr = aa.substr(6,2);
        if (parseInt(yr) < 50) { yr = '20'+yr; } else { yr = '19'+yr; }
        dt1 = yr+aa.substr(3,2)+aa.substr(0,2);
    }
    if (bb.length == 10) {
        dt2 = bb.substr(6,4)+bb.substr(3,2)+bb.substr(0,2);
    } else {
        yr = bb.substr(6,2);
        if (parseInt(yr) < 50) { yr = '20'+yr; } else { yr = '19'+yr; }
        dt2 = yr+bb.substr(3,2)+bb.substr(0,2);
    }
    if (dt1==dt2) return 0;
    if (dt1<dt2) return -1;
    return 1;
}

function ts_sort_currency(a,b) {
    aa = ts_getInnerText(a.cells[SORT_COLUMN_INDEX]).replace(/[^0-9.]/g,'');
    bb = ts_getInnerText(b.cells[SORT_COLUMN_INDEX]).replace(/[^0-9.]/g,'');
    return parseFloat(aa) - parseFloat(bb);
}

function ts_sort_numeric(a,b) {
    aa = parseFloat(ts_getInnerText(a.cells[SORT_COLUMN_INDEX]));
    if (isNaN(aa)) aa = 0;
    bb = parseFloat(ts_getInnerText(b.cells[SORT_COLUMN_INDEX]));
    if (isNaN(bb)) bb = 0;
    return aa-bb;
}

function ts_sort_caseinsensitive(a,b) {
    aa = ts_getInnerText(a.cells[SORT_COLUMN_INDEX]).toLowerCase();
    bb = ts_getInnerText(b.cells[SORT_COLUMN_INDEX]).toLowerCase();
    if (aa==bb) return 0;
    if (aa<bb) return -1;
    return 1;
}

function ts_sort_default(a,b) {
    aa = ts_getInnerText(a.cells[SORT_COLUMN_INDEX]);
    bb = ts_getInnerText(b.cells[SORT_COLUMN_INDEX]);
    if (aa==bb) return 0;
    if (aa<bb) return -1;
    return 1;
}


function addEvent(elm, evType, fn, useCapture)
// addEvent and removeEvent
// cross-browser event handling for IE5+,  NS6 and Mozilla
// By Scott Andrew
{
  if (elm.addEventListener){
    elm.addEventListener(evType, fn, useCapture);
    return true;
  } else if (elm.attachEvent){
    var r = elm.attachEvent("on"+evType, fn);
    return r;
  } else {
    alert("Handler could not be removed");
  }
}


I'd like to optimize it a bit so that it's as fast as possible, particularly so that it doesn't take long when sorting large tables.

Also, I'd like to give every other row a class so it's possible to style it with stripes. Since the rows are already iterated over to do the sorting, I thought it'd be simple to add this, but I'm really lost. I'm not familiar with JS to figure out what to do. I can't assign the classes when creating the table with PHP because they'll be messed up when re-sorting the table.

Any help will be greatly appreaciated.

[[Unknown]]

Find:

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for (i=0;i<newRows.length;i++) { if (!newRows[i].className || (newRows[i].className && (newRows[i].className.indexOf('sortbottom') == -1))) table.tBodies[0].appendChild(newRows[i]);}

Replace:

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var alternator = true;
for (i = 0; i < newRows.length; i++)
{
   if (!newRows[i].className || (newRows[i].className && (newRows[i].className.indexOf('sortbottom') == -1)))
   {
      newRows[i].className = alternator ? "class1" : "class2";
      alternator = !alternator;

      table.tBodies[0].appendChild(newRows[i]);
   }
}

Untested, of course.

-[Unknown]

[Anguz]

It worked! Only after the re-sorting the table, though. The original sort doesn't go throught that function yet so it's not striped. I'm guessing that onload striping should be done in ts_makeSortable... how would that go?

* Anguz tries his hand at it from what [Unknown] showed him...

YAY! Looks like it worked... I added this at the end of that function:

Code Select Expand


var alternator = true;
for (var i = 1; i < table.rows.length; i++)
{
table.rows[i].className = alternator ? "class1" : "class2";
alternator = !alternator;
}


Thank you [Unknown]

Now to the optimization, is there anything that could be done to make it faster? Not that it's normally slow, but I did try it with a very large table, several columns and rows, and it did lag.

[Anguz]

Got it working without the alternator, using % instead.

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for (var i = 1; i < table.rows.length; i++)
table.rows[i].className = i % 2 ? "class1" : "class2";


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for (var i = 0; i < newRows.length; i++)
{
if (!newRows[i].className || (newRows[i].className && (newRows[i].className.indexOf('sortbottom') == -1)))
{
newRows[i].className = i % 2 ? "class2" : "class1";
table.tBodies[0].appendChild(newRows[i]);
}
}